1. Field of the Invention
The present invention relates in general to video cassette recorders, and more particularly to a video cassette recorder (VCR) and a method of displaying time thereof, which are capable of receiving current time data transmitted from a broadcasting station and displaying the received data on a cathode ray tube (CRT) of a TV set or a monitor.
2. Description of the Prior Art
In conventional VCRs, there has been no means for automatically setting the current time upon power-on after a power-off or an interruption of power. For this reason, the user has to manually set the current time, which is an inconvenient.
To solve this problem, a device for detecting a time siren of a broadcasting signal from a broadcasting station and correcting the current time according to the detected time siren has been proposed, and one example of this form is shown in Korean Utility Model application No. 87-23800, filed by GOLDSTAR CO., Ltd. This device is frequently misoperated since it detects the time siren by detecting an aural level. Also, in this case, much time is required in correcting the current time according to the time siren upon power-on after a power-off or an interruption of power, since the time siren is transmitted at a long interval from the broadcasting station. For example, in Korea, the time siren is transmitted once a day from the broadcasting station.
A VCR having a time display function is adapted to control various functions using the current time. For example, the current time becomes an operating basis to control functions such as reserve-recording, automatic playback, etc. For this reason, when the current time is incorrect, a desired broadcasting program may not be recorded in the reserve-recording mode or may be played back in the playback mode during the user's absence. Therefore, there has been required an arrangement which is capable of making the current time being displayed by a digitron display unit of the VCR correct and correcting a time error due to power-off or a crystal oscillator of the VCR at any time.
Many studies of time display apparatus have been made by watch manufacturing companies. One example of them is disclosed in U.S. Pat. No. 4860268, designed to Junghance CO., Ltd., Germany, and is shown in FIG. 1, herein. In this patent, the time display apparatus contains a receiving circuit for receiving current time data which is placed on an amplitude modulation (AM) frequency and corrects the current time of a watch section by decoding the received current time data.
As shown in FIG. 1, the conventional time display apparatus comprises an amplifying and demodulating circuit 3 for receiving, through a receiving antenna 2, current time data which is AM-modulated in a broadcasting station and transmitted through a transmitting antenna 1. The circuit 3 amplified and demodulates the received current time data, and a time equalizing processor 4 for compares the current time from the amplifying and demodulating circuit 3 with the current time displayed on a watch section 5 and corrects the current time on the watch section 5 in accordance with the compared result.
To correct the current time, broadcasting stations for transmitting the AM frequency of a low frequency band have been established in countries such as U.S.A. and Germany. Also, watch products which contain the current time data receiving circuit and correct the current time of the watch section by decoding the received current time data are available from the watch manufacturing companies such as, for example, Junghance CO., Ltd., Germany.
However, the watch products available from Junghance CO., Ltd. and the time display apparatus in the above patent operate only to correct a faulty operation or a time error of the mechanical watch section. In particular, the time equalizing processor merely functions to decode the current time data, detect the current time of the watch section, and correct the current time of the watch section as a result of the comparison of the decoded current time data and the detected current time. Also, the current time data contains only hour and minute information without the second information. Further, the time equalization processor 4 continues to receive and process the current time data and subjected to an overload.
Also, the Junghance's watch products and patent have the following disadvantages when they are applied to the VCR, because they can be applied to only the watch fields.
First, there is no requirement to compare the decoded current time data with the detected current time, because a time display apparatus is driven by an electronic counter. For this reason, the time equalizing processor is unnecessary for the VCR.
Second, the VCR requires very accurate time which is beyond the capability of a simple control unit such as the time equalizing processor.